A Survey of Hot Gas in the Universe

TL;DR

This survey reviews the detection and analysis of hot, X-ray emitting gas in the universe's extended structures, highlighting the importance of grating spectrometers for future astrophysical research.

Contribution

It summarizes recent advancements in X-ray spectroscopy techniques for studying hot gas in galaxy environments and emphasizes the role of grating spectrometers in future missions.

Findings

Detection of hidden metals and mass in galaxy halos and the cosmic web.

Quantification of hot gas flows, turbulence, and rotation around galaxies.

Demonstration of the capabilities of grating spectrometers for future X-ray observations.

Abstract

A large fraction of the baryons and most of the metals in the Universe are unaccounted for. They likely lie in extended galaxy halos, galaxy groups, and the cosmic web, and measuring their nature is essential to understanding galaxy formation. These environments have virial temperatures >10^5.5 K, so the gas should be visible in X-rays. Here we show the breakthrough capabilities of grating spectrometers to 1) detect these reservoirs of hidden metals and mass, and 2) quantify hot gas flows, turbulence, and rotation around the Milky Way and external galaxies. Grating spectrometers are essential instruments for future X-ray missions, and existing technologies provide 50-1500-fold higher throughput compared to current orbiting instruments.